Mechanical Engineering Commons^™

Computational Study Of Heat Transfer Enhancement For A Dimpled Surface In A Channel, Abhijit Paranjape

Mechanical and Aerospace Engineering Theses - Archive

Heat transfer augmentation techniques have gained great importance in different engineering applications to deal with thermal management issues. In this work, a numerical investigation was carried out to see the effects of spherical dimple arrays on heat transfer characteristics in a channel. These effects were observed for dimples on the bottom wall of the channel for laminar airflows. The effects of a 21×7 staggered array and a 19×4 inline array on the bottom wall were investigated using a 3D steady viscous computational fluid dynamics package with an unstructured grid. The heat transfer characteristics were studied as a function of the …

Spur Gear Analysis Using Mathcad, Jaydeep K. Panchal

Mechanical and Aerospace Engineering Theses - Archive

In gear manufacturing applications, it is required to calculate surface stress and bending stress with minimum error. This thesis represents engineering calculation of bending and surface compression of external teethed involute spur gear. One may change the input values to calculate the engineering data for gears. The freedom of changing input values gives the capability to program to calculate for factor, Y; and the bending geometry factor, J to analyze spur gear geometry. Here the engineering gear calculation has been done by developing program in Mathcad software. The program is designed to calculate surface and bending stress data by input …

Torsional Analysis Of A Composite I-Beam, Vishal Mukesh Smita Sanghavi

Mechanical and Aerospace Engineering Theses - Archive

A simple methodology for analysis of thin walled composite I-Beam subjected to free torsion and restrained torsion is developed. Classical Lamination Theory is extended from the laminate level to the structural level for analysis purpose.The developed expressions for shear center, equivalent torsional rigidity and equivalent warping rigidity for a composite mono-symmetric I-Beam depends on the material properties, ply stacking sequence, fiber orientation and geometryThe results from the proposed theory gives better agreement with the ANSYS^TM results than the traditional smeared property approach.

Control Of A Teleoperating Robotic Arm Subject To Time Delays, Pankaj Prakash Sarda

Mechanical and Aerospace Engineering Theses - Archive

Robotics in Minimally Invasive Surgeries (MIS) can be explored to its full potential if there is complete transparency between the surgeon and the virtual environment. In the setup, haptic device which conveys force from the surgeon to the surgery site and vice verse acts as the master station and robotic arm at the surgery site acts as the slave robot. In surgeries carried out remotely, time delays in the communication channels can cause commanded velocity/force to overshoot before the surgeon can even pull out during a task causing temporary or permanent damage during the surgery. Since the physical capability of …

Study Of The Surface Roughness Evolution In Fatigued 316l Stainless Steel, Ye Wang

Mechanical and Aerospace Engineering Theses - Archive

Fatigue is a critical design consideration in many aerospace structures. As improvements are sought in overall performance, maintenance requirements, and total service life of modern aircrafts, the demands for fatigue control techniques, such as material design for fatigue resistance, reliable fatigue life prediction, and continuous material damage monitoring, have increased. The most common practices to ensure fatigue safety include: fracture mechanics based fatigue life prediction, periodic non-destructive inspections, and material processing control. Reasonable successes have been achieved by applying these three techniques to ensure the safe operation of aerospace structures. It is worth mentioning that most of the present fatigue …

New Developments In Cognitive Optimization, Parvati Aruna Kandala

Mechanical and Aerospace Engineering Theses - Archive

This work presents an approach to solve function optimization problems using cognitive optimization. A cognitive search algorithm which is developed mimics human cognition in structure and characteristics. This algorithm is developed based on the key aspects of a cognitive system, namely, the use of prior knowledge, communication, and self-organization. The processes have the knowledge of how to solve the optimization problems from traditional techniques such as bracketing, gradient search and interval-halving methods. This search algorithm shows that, by passing messages, the processes communicate, share information, and self-organize around the solution. A mat lab program is coded to perform the tests …

Transient Analysis Of A Pulsed Detonation Combustor Using The Numerical Propulsion System Simulation, Anthony Scott Hasler

Mechanical and Aerospace Engineering Theses - Archive

The performance of a hybrid mixed flow turbofan (with detonation tubes installed in the bypass duct) is investigated in this study and compared with a baseline model of a mixed flow turbofan with a standard combustion chamber as a duct burner. Previous studies have shown that pulsed detonation combustors have the potential to be more efficient than standard combustors, but they also present new challenges that must be overcome before they can be utilized. The Numerical Propulsion System Simulation (NPSS) will be used to perform the analysis with a pulsed detonation combustor model based on a numerical simulation done by …

Analytical Method For Analyzing C-Channel Stiffener Made Of Laminate Composite, Tattchapong Kumton

Mechanical and Aerospace Engineering Theses - Archive

Composite materials play the important role in the aviation industry. Conventional materials such as aluminum were replaced by composite material on the main structures. The objective of this study focuses on development of analytical method to analyze the laminated composite structure with C-channel cross-section. A lamination theory base closed-form solution was developed to analysis ply stresses on the C-channel cross-section. The developed method contains the effects of coupling due to unsymmetrical of both laminate and structural configuration levels. The present method also included the expression of the sectional properties such as centroid, axial and bending stiffnesses of cross-section. The results …

Particle Advection Using The Lattice-Boltzmann Method, Matthew Carroll

Mechanical and Aerospace Engineering Theses - Archive

Lattice-Boltzmann Method (LBM) CFD analysis can be helpful in analysing fluid flow through porous media and complex geometries that may be difficult to simulate using traditional CFD methods. In this thesis, the technical details of lattice Botlzmann particle advection are presented. The lattice Botlzmann equations are explained as well as a method for introducing a particle in a fluid flow and advecting the particle using viscous, pressure, and gravitational forces. A method is developed to advect a particle through a computational lattice mesh using pressure forces, gravitational forces, as well as LBM-specific viscous force equations. The capability of the particle …

Stress Concentrations Around A Square Cutout In A Composite Plate, Colin Cannon

Mechanical and Aerospace Engineering Theses - Archive

Composite structure in the aircraft industry has been in development for well over half a century and yet the understanding of the effects of a square cutout is generally limited to quasi-isotropic laminates. Currently, the closed-form solution to calculate the stresses around a cutout is limited to symmetric anisotropic laminates with limitations on the cutout shapes. Finite Element Analysis, using MSC PATRAN and NASTRAN, was performed on 2D composite laminates containing square cutouts with rounded corners. The laminate stacking sequence was varied from symmetrical and balanced to unsymmetrical and unbalanced and the square cutouts each had different radii at the …

Cfd Based Aerodynamic Modeling To Study Flight Dynamics Of A Flapping Wing Micro Air Vehicle, Alok Ashok Rege

Mechanical and Aerospace Engineering Theses - Archive

The demand for small unmanned air vehicles, commonly termed micro air vehicles or MAV's, is rapidly increasing. Driven by applications ranging from civil search-and-rescue missions to military surveillance missions, there is a rising level of interest and investment in better vehicle designs, and miniaturized components are enabling many rapid advances. The need to better understand fundamental aspects of flight for small vehicles has spawned a surge in high quality research in the area of micro air vehicles. These aircraft have a set of constraints which are, in many ways, considerably different from that of traditional aircraft and are often best …

Impact Of Louver Orientation On Air Flow Distribution And Thermal Management Of Data Centers, Kushal A. Aurangabadkar

Mechanical and Aerospace Engineering Theses - Archive

Nowadays with the increasing use of technology, Traditional data centers are being replaced by the highly efficient Containerized or Modular Data centers. The cooling systems and constructional cost employed for Traditional Data centers is more and inefficient. The research intricate, about 23% of the power is consumed by HVAC cooling units and which in turn leads to increase in operational costs. Hence in order to reduce the operational costs, free cooling with Air side economizer is incorporated, compared to other cooling systems. Airflow Distribution plays an important role in the Thermal management, if the airflow is less in quantity it …

Assessment Of The Mechanical Integrity Of Cu/Low-K Dielectric In A Flip Chip Package, Thiagarajan Raman

Mechanical and Aerospace Engineering Theses - Archive

Miniaturization and more recently convergence have been driving the industry since the invention of the transistor and integrated circuit (IC). Though the gate delay has decreased with transistor scaling, the increase in the resistive capacitive (RC) interconnect delay due to shrinking interconnect dimensions has become a serious concern for the development of future-generation electronics. To reduce the delay due to resistance R, a major technology change was the replacement of Aluminum (Al) with Copper (Cu) interconnect layers in the BEoL (Back-end-of-line). Recently, some investigators have suggested using low-k dielectric (having dielectric constant less than 4) instead of SiO2 (k= 3.9) …

Numerical Study Of Sidewall Filling For Gas-Fed Pulse Detonation Engines, Wunnarat Rongrat

Mechanical and Aerospace Engineering Theses - Archive

Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to ll the tube at …

Thermal Analysis Of High End Servers Based On Development Of Detail Model And Experiments, Shreyas Sampath

Mechanical and Aerospace Engineering Theses - Archive

Thermal management of an efficient data center can be primarily dictated by efficient servers. Continued increase in power density and power dissipation of high end processors, thermal analysis and management has made it strategically important in the challenge of advanced thermal solutions. Present day CFD software provides powerful tools to create very accurate fluid and heat transfer solutions. Validation of a detailed model of a server in CFD corresponds to accurate flow and temperature models and these detailed server models are the foundational blocks for accurate data center thermal management solutions. In this research, an experimental study of the thermal …

Design Charts For Circular Fins Of Arbitrary Profile Subject To Radiation And Convection With Wall Resistances, G. Zhang, Benjamin T.F. Chung

Mechanical Engineering Faculty Research

In this work, the optimization for a radiative-convective annular fin of arbitrary profile with base wall thermal resistances is considered. A fourth order Runge-Kutta method is used to solve the associated non-linear governing equa-tions. Further differentiations yield the optimum heat transfer and the optimum fin dimensions. To facilitate the thermal design, design charts for optimum dimensions are proposed. Furthermore, the fin effectiveness for the optimal annular ra-diative-convective fins is presented to check the practicality of the design.

http://dx.doi.org/10.2174/1874396X01206010015

Factors Impacting Technology Transfer: The Maquiladora Industry In Yucatan, Mexico, Ana Maria Canto, Carlos Blanco, Pilar Pazos

Engineering Management & Systems Engineering Faculty Publications

Technology transfer and knowledge transfer are the building blocks for innovation, efficiency and increased competitiveness. The topic of technology transfer in the context of multinational companies has been the focus of technology management researchers for well over two decades. Developing countries housing twin plans have been exposed to technology transfer from very diverse countries with different approaches to the technology transfer process and different levels of success. This cultural and national diversity adds an additional level of complexity to the technology transfer domain that has been largely unexplored. This paper will explore critical factors that had an impact in successful …

Investigating The Effects Of Internally Trapped Residuals On The Performance Of A Homogeneous Charge Compression Ignition (Hcci) Engine, Aaron David Attebery

Masters Theses

"Homogeneous charge compression ignition (HCCI) combustion introduces great opportunity for decreased emissions along with greater engine efficiencies. Implementing an innovative combustion mode such as HCCI presents a great challenge for the engine research community. One such challenge is controlling the innate cyclic variability from this chemical kinetics controlled auto-ignition event when transitioning to or from a SI operating mode. This work includes the study of cycle-to-cycle dynamics that occur within the partial burn regime of an HCCI engine as it approaches the misfire limit. Within this regime there are many successive incomplete combustion events that will impact the next cycle …

Force Sensing Of An Asymmetric Dielectric Barrier Discharge Using Mechanical Resonators, Mark Dawson Emanuel

Masters Theses

"Dielectric barrier discharge (DBD) plasma actuators are of great interest in flow control research and application. DBD plasma actuators are low-cost, lightweight, high voltage devices that have the capability of generating small amounts of thrust on the order of a few tenths of a gram. The thrust is created by rapidly pulsing plasma discharges which correlate to the frequency of the applied alternating current waveform, in the low kilohertz range.

Plasma actuators experience a reactant force generated by the pulsed plasma charging and then expelling air away from the charged surface. This force fluctuates with time as the plasma is …

New Detonation Concepts For Propulsion And Power Generation, Eric Braun

Mechanical and Aerospace Engineering Dissertations - Archive

A series of related analytical and experimental studies are focused on utilizing detonations for emerging propulsion and power generation devices. An understanding of the physical and thermodynamic processes for this unsteady thermodynamic cycle has taken over 100 years to develop. An overview of the thermodynamic processes and development history is provided.Thermodynamic cycle analysis of detonation-based systems has often been studied using surrogate models. A real gas model is used for a thermal efficiency prediction of a detonation wave based on the work and heat specified by process path diagrams and a control volume analysis. A combined first and second law …

Hygrothermally Stable Laminated Composites For Optimal Extension Twist Coupling In Closed Cell Configuration, Sean Muder

Mechanical and Aerospace Engineering Theses - Archive

An optimization routine utilizing the sequential quadratic programming method is used to develop laminates that are hygrothermally stable in flat-strip configuration and are optimal for extension twist coupling in closed cell configuration. The performance of the laminates obtained from the optimization in terms of the level of extension twist coupling and hygrothermal stability are evaluated and compared to laminates from a previous routine. A parametric study is conducted to illustrate the relationships between the geometric dimensions of a representative closed cell section and the level of extension twist coupling. Results from the parametric study suggested a more practical optimization approach …

Design, Calibration And Testing Of A Force Balance For A Hypersonic Shock Tunnel, Pravin Vadassery

Mechanical and Aerospace Engineering Theses - Archive

The forces acting on a flight vehicle are critical for determining its performance. Of particular interest is the hypersonic regime. Force measurements are much more complex in hypersonic flows, where those speeds are simulated in shock tunnels. A force balance for such facilities contains sensitive gages that measure stress waves and ultimately determine the different components of force acting on the model. An external force balance was designed and fabricated for the UTA Hypersonic shock tunnel to measure drag at Mach 10. Static and dynamic calibrations were performed to find the transfer function of the system. Forces were recovered using …

Guidance And Control Of Unmanned Airships For Waypoint Navigation In The Presence Of Wind, Ghassan M. Atmeh

Mechanical and Aerospace Engineering Theses - Archive

Airships are a specific class of Lighter-Than-Air (LTA) vehicles. These vehicles achieve lift mainly through buoyancy; the usually ellipsoidal shaped hull contains a lifting gas such as helium, which produces the required lift though air displacement. Due to this method of operation an airship has the ability to conduct low-power hover, which makes it ideal for applications requiring hovering over long periods of time such as surveillance, terrain mapping, meteorology and GPS. In such applications the conventional fixed wing unmanned aircraft is less suitable. The work presented in this thesis deals with designing a controller that is capable of navigating …

Heat Transfer Enhancement In A Rectangular Channel Using Vortex Generator In A Laminar Flow, Ninad C. Maniar

Mechanical and Aerospace Engineering Theses - Archive

Enhancement of heat transfer through various means has been an intense area of research for many years. There are numerous applications where high performance heat exchange is desired. The cooling of electronics, such as microprocessors, is one example. The recent rise in the studies of heat exchange enhancement techniques has also lead to efficient and compact heat exchangers. This research involves the numerical analysis of heat exchange enhancement in a rectangular channel using different types of longitudinal vortex generators (LVG) for a laminar flow. A computational fluid dynamics software package was used to compute the 3-D steady viscous flows with …

Cfd Analysis Of Direct Evaporative Cooling Zone Of Air-Side Economizer For Containerized Data Center, Niket Shah

Mechanical and Aerospace Engineering Theses - Archive

Conventional data centers are extremely large buildings that have complex power distribution and cooling systems. These traditional brick and mortar data centers employ relatively expensive cooling systems and are inefficient. It has in turn led to an increase in construction and operational costs. Jonathan Koomey, Ph.D. of Lawrence Berkeley National Laboratory estimated that worldwide data center power consumption was 152.5 Billion kWh in 2005. In 2007, the US EPA estimated that servers and data centers, “consumed about 61 billion kilowatt-hours (kWh) in 2006 (1.5 percent of total U.S. electricity consumption) for a total electricity cost of about $4.5 billion. These …

Dechlorination Of Environmental Contaminants Using A Hybrid Nanocatalyst: Palladium Nanoparticles Supported On Hierarchical Carbon Nanostructures, Hema Vijwani, Abinash Agrawal, Sharmila M. Mukhopadhyay

Mechanical and Materials Engineering Faculty Publications

This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam) and foam with carbon nanotubes anchored on the pore walls (CNT/Foam). Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation …

Numerical Simulation Of Electrolyte-Supported Planar Button Solid Oxide Fuel Cell, Amjad Aman

Electronic Theses and Dissertations

Solid Oxide Fuel Cells are fuel cells that operate at high temperatures usually in the range of 600oC to 1000oC and employ solid ceramics as the electrolyte. In Solid Oxide Fuel Cells oxygen ions (O2- ) are the ionic charge carriers. Solid Oxide Fuel Cells are known for their higher electrical efficiency of about 50-60% [1] compared to other types of fuel cells and are considered very suitable in stationary power generation applications. It is very important to study the effects of different parameters on the performance of Solid Oxide Fuel Cells and for this purpose the experimental or numerical …

Fire Retardant Polymer Nanocomposites: Materials Design And Thermal Degradation Modeling, Jinfeng Zhuge

Electronic Theses and Dissertations

Compared to conventional materials, polymer matrix composites (PMCs) have a number of attractive properties, including light weight, easiness of installation, potential to lower system-level cost, high overall durability, and less susceptibility to environmental deterioration. However, PMCs are vulnerable to fire such that they degrade, decompose, and sometimes yield toxic gases at high temperature. The degradation and decomposition of composites lead to loss in mass, resulting in loss in mechanical strength. This research aims to improve the structural integrity of the PMCs under fire conditions by designing and optimizing a fire retardant nanopaper coating, and to fundamentally understand the thermal response …

Optimization Of Ocean Thermal Energy Conversion Power Plants, Steven Emanoel Rizea

Electronic Theses and Dissertations

A proprietary Ocean Thermal Energy Conversion (OTEC) modeling tool, the Makai OTEC Thermodynamic and Economic Model (MOTEM), is leveraged to evaluate the accuracy of finite-time thermodynamic OTEC optimization methods. MOTEM is a full OTEC system simulator capable of evaluating the effects of variation in heat exchanger operating temperatures and seawater flow rates. The evaluation is based on a comparison of the net power output of an OTEC plant with a fixed configuration. Select optimization methods from the literature are shown to produce between 93% and 99% of the maximum possible amount of power, depending on the selection of heat exchanger …

Virtual Motion Camouflage Based Nonlinear Constrained Optimal Trajectory Design Method, Gareth Basset

Electronic Theses and Dissertations

Nonlinear constrained optimal trajectory control is an important and fundamental area of research that continues to advance in numerous fields. Many attempts have been made to present new methods that can solve for optimal trajectories more efficiently or to improve the overall performance of existing techniques. This research presents a recently developed bio-inspired method called the Virtual Motion Camouflage (VMC) method that offers a means of quickly finding, within a defined but varying search space, the optimal trajectory that is equal or close to the optimal solution. The research starts with the polynomial-based VMC method, which works within a search …